JPH093272A - Polypropylene resin composition - Google Patents

Abstract

PURPOSE: To obtain the subject composition capable of suppressing peeling of surface layer, keeping general properties of polypropylene resin, improved in mechanical strength, heat resistance and friction property and useful for electronic parts, etc., by blending a polypropylene resin with a specific branched polyacetal resin in a specific ratio. CONSTITUTION: This composition is obtained by blending (A) 100 pts.wt. of polypropylene resin with (B) 3 to 100 pts.wt. of a branched polyacetal resin prepared by copolymerizing 99.8 to 85.00wt.% trioxane with 0.1 to 10wt.% cyclic ether or cyclic formal (e.g. a compound of formula I R<1> to R<4> are each H, a (haloganated) alkyl; R<5> is [1-3 (haloganated) 1-5C alkyl-substituted] (oxy) methylene; p is 0-3 ) and 0.02 to 5wt.% diglycidil compound e.g. a compound of formula II [n is 2-6]}.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polypropylene resin composition based on polypropylene resin and obtained by alloying a specific branched polyacetal resin, which has excellent frictional properties and high mechanical strength.
More specifically, the present invention provides a polypropylene resin composition having an increased mechanical strength / elastic modulus and excellent friction / wear characteristics without impairing the moldability and toughness of the polypropylene resin. The polypropylene resin composition of the present invention Is suitably used for large-sized molded articles such as containers, various electric / electronic parts, and automobile parts.

[0002]

2. Description of the Related Art Polypropylene resin is inexpensive, lightweight and excellent in electrical properties, chemical properties, moldability, etc., and therefore, mechanical parts, containers,
It is widely used in various fields as various films, sheets, tapes, insulating parts, coating materials, etc. However, it has drawbacks that it is easily scratched due to its low surface hardness, its rigidity and elastic modulus are low, and its friction and wear characteristics are poor. Therefore, it could not be sufficiently used in a portion (for example, a sliding member) where such characteristics are required. In order to improve these points, a method of blending various fillers such as glass fibers or a lubricant such as fatty acid ester and silicone oil has been attempted. However, the compounding of the filler has a problem that molding cannot be performed in applications such as thin-walled molded articles that require fluidity. On the other hand, although the addition of a lubricant is recognized to have some improvement in friction and wear properties, there is a problem that the surface hardness is further lowered. Therefore, blending with a tough resin represented by a polyacetal resin or a polyester resin has been attempted. However, the polypropylene resin and these compounded resins are poorly mixed, and dispersion failure occurs simply by melt-kneading, and toughness cannot be obtained, as well as appearance of the surface of the molded product due to surface layer peeling or flow marks. There are problems such as damage, and it has not been put to practical use.

[0003]

[Means for Solving the Problems] As a result of intensive studies conducted by the present inventors in order to solve the above problems, as a result of surface layer peeling and flow marks when a polypropylene resin is blended with a polyacetal resin, high shear during molding is observed. It was found that the force causes the polyacetal resin of the domain to be expanded from particles to fine needles.By making the polyacetal resin have a branched structure, it will not be expanded into fine needles even under high shear during molding. And succeeded in completing the present invention. That is, the present invention is (A) polypropylene resin
Branched polyacetal obtained by polymerizing 100 parts by weight of (B) 99.88 to 85.00% by weight of trioxane, 0.1 to 10% by weight of cyclic ether and / or cyclic formal, and 0.02 to 5% by weight of diglycidyl compound. The present invention relates to a polypropylene resin composition containing 3 to 100 parts by weight of a resin.

Hereinafter, the raw material compounds necessary for forming the polypropylene resin composition of the present invention will be described in detail in order. First, the (A) polypropylene resin of the present invention is a polymer containing propylene as a main component, and has a propylene component amount of 100 to 70 mol%. If the propylene component is less than 70 mol%, the mechanical strength is significantly reduced, which is not preferable. Further, the copolymerization component is ethylene, butylene, pentene or the like, and ethylene is most preferable.

It is important that the branched polyacetal resin used as the component (B), when blended with the polypropylene resin, is not elongated from particles into fine needles even under shearing during molding. It is characterized in that the molecular structure is not linear but has a branched (or crosslinked) structure. (B) Trioxane and comonomer, which are the main monomers constituting the branched polyacetal resin, are well-known substances conventionally used in the production of polyacetal resin. That is, trioxane is a cyclic trimer obtained from formaldehyde. The cyclic ether and cyclic formal as the comonomer are compounds represented by the following general formula (1).

[0006]

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[In the formula, R ¹ , R ² , R ³ and R ⁴ represent a hydrogen atom, an alkyl group or an alkyl group substituted with a halogen, and may be the same or different. R ⁵ is a methylene group, an oxymethylene group, a methylene group substituted by an alkyl group or a halogenated alkyl group, or an oxymethylene group (in this case, p represents an integer of 0 to 3), or a formula- (CH ₂ ) ₄ -OCH _2- or-(O-CH ₂ -CH ₂ ) _q -OCH ₂
It means a divalent group represented by-(wherein q represents an integer of 1 to 4). The alkyl group has 1 to 5 carbon atoms,
1 to 3 hydrogens may be replaced by halogen atoms, especially chlorine atoms. Examples of such a cyclic ether or cyclic formal include epichlorohydrin, ethylene oxide, 1,3-dioxolane, diethylene glycol formal, 1,4-
Butanediol formal, 1,3-dioxane, propylene oxide and the like can be mentioned. Furthermore, cyclic esters such as β-propiolactone and vinyl compounds such as styrene or acrylonitrile are also used. Particularly preferred cyclic ethers and cyclic formal are one or more selected from ethylene oxide, dioxolane, trioxeban, and 1,4-butanediol formal. The amount of cyclic ether or cyclic formal used is 0.1 to 10% by weight, preferably 0.3 to 5%, based on the total amount of mixed monomers.
% By weight. If the amount is less than 0.1% by weight, the thermal stability, which is a characteristic of polyacetal resin, is insufficient, and if it exceeds 10% by weight, not only the mechanical strength decreases but also the manufacturing itself becomes difficult, and the improvement of properties by alloying I can not expect it. Next, the diglycidyl compound that causes branching in the polyacetal resin, which is a feature of the present invention, will be described.
The diglycidyl compound used for the production of the polyacetal copolymer of the present invention is an aliphatic ether having two glycidyl groups at the ends, and preferably the compound represented by the following general formula (2) or (3) is used.

[0008]

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Examples of the diglycidyl compound represented by the above formula (2) or (3) include diethylene glycol diglycidyl ether, triethylene glycol diglycidyl ether, butanediol diglycidyl ether, and the like. Butanediol diglycidyl ether is particularly preferable. Is. The amount of the diglycidyl compound used is 0.02 to
It is 5.0% by weight, preferably 0.1 to 3.0% by weight. 0.02
If the amount is less than 5% by weight, peeling is likely to occur during alloying with polypropylene resin, and 5.0% by weight
If the amount is larger than the above range, an excessive crosslinking reaction will occur during the polymerization, which makes the production itself difficult, and the processability, mechanical strength, etc. of the polymerized product will be significantly reduced, which is not preferable.

Polymerization of such a polyacetal copolymer is
It may be carried out according to the polymerization of a trioxane copolymer which is generally well known. That is, a cation active catalyst is generally used as the catalyst. Specific examples of such catalysts include Lewis acids, particularly halides such as boron, tin, titanium, phosphorus, arsenic and antimony, such as boron trifluoride, tin tetrachloride, titanium tetrachloride, phosphorus pentachloride and pentapentane. Compounds such as phosphorus fluoride, arsenic pentafluoride and antimony pentafluoride, and complex compounds or salts thereof, protic acids such as trifluoromethanesulfonic acid, perchloric acid, esters of protic acids, especially perchloric acid and lower aliphatic alcohols. An ester of perchloric acid (for example, perchloric acid tertiary butyl ester), an anhydride of a protic acid, particularly a mixed anhydride of perchloric acid and a lower aliphatic carboxylic acid (for example, acetyl perchlorate), or an isopoly acid, a heteropoly acid (for example, Phosphomolybdic acid), or triethyloxonium hexafluorophosphate, triphenyl Chill hexafluoro ARUZE diisocyanate, acetyl hexafluoro borate and the like. Among them, boron fluoride or a coordination compound of boron fluoride and an organic compound (for example, ethers) is the most common and suitable. The polymerization reaction may be batch type, continuous type, or any of solution polymerization, melt bulk polymerization, etc., but a method of using a liquid monomer to obtain a solid powdery bulk polymer as the polymerization proceeds It is common. In this case, an inert liquid medium can coexist as necessary. The amount of such (B) branched polyacetal resin added is (A) polypropylene resin 100
3 to 100 parts by weight, preferably 5 to 70 parts by weight
Parts by weight. If this amount is less than 3 parts by weight, the mechanical strength and friction and wear properties are not sufficiently improved, and if it exceeds 100 parts by weight, the branched polyacetal resin partially forms a continuous phase in the polypropylene resin. The particle dispersion of the domain is not achieved, and problems such as peeling occur.

In the present invention, the above-mentioned (B) branched polyacetal resin is used as a domain to suppress the layered dispersion in the vicinity of the surface layer even under shearing during molding, but in the present invention, the affinity at the matrix-domain interface is further improved. Therefore, it is more preferable to blend a polyisocyanate or a modified product thereof and a modified polypropylene having an active hydrogen group capable of reacting with an isocyanate group. Hereinafter, the polyisocyanate or a modified product thereof and a modified polypropylene having an active hydrogen group capable of reacting with an isocyanate group will be described. First, the polyisocyanate compound or its modified product is a compound having an iso (thio) cyanate group in the molecule, and a compound having two or more iso (thio) cyanate groups in one molecule. For example,
4,4'-methylenebis (phenylisocyanate),
2,4-Tolylene diisocyanate, 2,6-Tolylene diisocyanate, Xylene diisocyanate, 1,6
-Hexamethylene diisocyanate, isophorone diisocyanate, 1,5-naphthalene diisocyanate, or their corresponding diisothiocyanates, and their dimers, trimers, and further isocyanate groups (-N
CO) can be used in any form, but in consideration of properties such as discoloration degree such as melt processing and safety in handling, 4,4′-methylenebis (phenylisocyanate) , Isophorone diisocyanate, 1,5-naphthalene diisocyanate,
2,4-Tolylene diisocyanate, 2,6-Tolylene diisocyanate, 1,6-hexamethylene diisocyanate, and modified products (or derivatives) such as dimers and trimers thereof are particularly preferable. The compounding amount of polyisocyanate or its modified product must be in the range of 0.01 to 15 parts by weight with respect to 100 parts by weight of the polypropylene resin (A).
If the blending amount exceeds 15 parts by weight, gelation occurs and the fluidity and the resin properties are deteriorated, which is not preferable. Next, a modified polypropylene having an active hydrogen group capable of reacting with an isocyanate group is an active hydrogen group capable of reacting with and binding to an isocyanate group in a molecule, that is, a hydroxyl group, a carboxyl group, a primary or secondary amino group. , Modified polypropylene containing amide groups and the like. Examples of the method for producing the modified polypropylene having an active hydrogen group include a method of introducing a monomer having an active hydrogen group at the time of polymerization, a method of oxidizing and decomposing polypropylene. As the active hydrogen group, an acrylic acid group or a hydroxyl group is particularly preferable, and its modification amount is preferably 0.1 to 10% by weight based on polypropylene. If the modification amount is less than 0.1% by weight, the effect of increasing the interfacial affinity between the matrix and the domain is not sufficient, and if it exceeds 10% by weight, gelation tends to occur, which is not suitable for the present invention. The average molecular weight of the modified polypropylene is not particularly limited, but a relatively low molecular weight is preferable, and an average molecular weight of 5,000 to 100,000 is particularly preferable in order to facilitate uneven distribution at the matrix-domain interface. further,
The main chain of modified polypropylene may be a copolymer obtained by copolymerizing ethylene, butene, hexene, etc. in addition to polypropylene homopolymer, but the propylene content is 80 mol.
% Is desirable. The amount of the modified polypropylene having an active hydrogen group capable of reacting with the isocyanate group is 0.1 to 30 parts by weight, and if it exceeds 30 parts by weight, gelation or thickening occurs, which is not preferable.

Further, the composition of the present invention may optionally contain additives such as an antioxidant, an ultraviolet absorber, a nucleating agent, a plasticizer, a lubricant, an antistatic agent, a flame retardant and a colorant. You may mix | blend arbitrary amounts in the range which does not impair the physical property of this invention. The composition obtained by the present invention can be molded by a usual method.

[0013]

EFFECT OF THE INVENTION The composition obtained by the present invention comprises a polypropylene resin and a polyacetal resin having a branched structure, so that the polypropylene resin retains its moldability and chemical resistance while maintaining its thermal properties and mechanical strength. The friction characteristics are improved, and further, peeling of the surface layer and deterioration of the weld characteristics caused by the conventional alloying are suppressed, and application to many uses can be expected.

[0014]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. Production example (synthesis of branched polyacetal resin B-1) Two circles with an inner diameter of 80 mm have a cross-section where some circles overlap, and an effective length
A continuous mixing reactor consisting of a barrel with a heat transfer medium on the outside of 1.3 m and two rotating shafts with multiple paddles that mesh with each other inside was used.
Passing hot water at ℃, rotate the two rotating shafts in different directions at a speed of 100 rpm. Continuously supplied at the same rate, at the same time, to the same place, a cyclohexane solution of dibutyl etherate of boron trifluoride was continuously added in a predetermined amount to perform copolymerization, and the reaction mixture discharged from the other end was Immediately, it was poured into water containing 0.1% of triethylamine to deactivate the polymerization catalyst. Next, the polymer was washed with acetone and then air-dried for stabilization to obtain a branched polyacetal copolymer (MI = 2.0). Reference Example (Synthesis of polyacetal copolymer B'-1) 96.95% by weight of trioxane, 3.0% by weight of dioxolane,
Polymerization was carried out in the same manner as in Production Example using a trioxane mixture containing 0.05% by weight of methylal, and a substantially linear polyacetal copolymer (MI = 2.2) was obtained through a stabilization process.

Examples 1 to 4 100 parts by weight of a polypropylene resin (manufactured by Mitsui Petrochemical Co., Ltd., polypropylene copolymer, J640: A-1) was mixed with the branched polyacetal resin B-1 synthesized above in an amount shown in Table 1, Using a 30 mm twin-screw extruder, the mixture was melt-kneaded at a setting of 200 ° C. and a screw rotation of 100 rpm to be pelletized. Next, the pellets were molded into test pieces by an injection molding machine, and the following evaluations were performed. Table 1 shows the evaluation results. <Tensile strength (weld)> With gates at both ends, thickness 2
mm weld test pieces were used, and the measurement method was in accordance with ASTM D-638. In addition, the same test was performed on the one-gate test piece to compare the strengths with and without welds. <Flexural modulus> Using a test piece with a thickness of 1/4 inch, ASTM
The flexural modulus was measured by D-790. <Deflection temperature under load> The deflection temperature under load was measured according to ASTM D-648. Measuring load is 4.6kgf / cm ² and 18.5kgf / cm
² <Surface Layer Peeling Test> Cellophane tape was attached to the surface of the test piece and peeled off, and then the peeling state was visually observed, and the evaluation was performed according to the following five grades. ◎ ... No peeling at all ○ ... Slight peeling at all △ ... Slight peeling at least × ・ ・ ・ Peeling over half of the pasted surface ×× …… Peeling at all pasted surface <Friction characteristics> Suzuki friction Abrasion test (contact area 2.0 cm ² ) is used, mating material metal (steel, S45C), linear velocity 150 mm / sec
The amount of resin abrasion was measured by sliding for 24 hours under a surface pressure of 2.5 kg / cm ² .

Examples 5 to 6 In addition to Example 1 (or 2), isophorone diisocyanate trimer and hydroxyl group-containing polypropylene (OH group-containing P
P; Sanyo Kasei Umex 1201H) was mixed in the amounts shown in Table 1, and a sample was prepared and evaluated in the same manner. Example 7 A sample was prepared and evaluated in the same manner as in Example 1 except that polypropylene homopolymer (J400: A-2, manufactured by Mitsui Petrochemical Co., Ltd.) was used as the polypropylene resin. Example 8 An isophorone diisocyanate trimer and a hydroxyl group-containing polypropylene (OH group-containing PP; Umex 1201H manufactured by Sanyo Kasei Co., Ltd.) were further added to Example 7 in the amounts shown in Table 1, and a sample was prepared and evaluated in the same manner. . Comparative Example 1 As shown in Table 2, the polypropylene resin A-1 used in Example 1
Was directly molded and evaluated. Comparative Examples 2 to 4 Samples were prepared in the same manner as in Example 1, 2 or 5 except that the substantially linear polyacetal resin B'-1 obtained in Reference Example was used instead of the branched polyacetal resin B-1. ,evaluated. Comparative Example 5 The polypropylene resin A-2 used in Example 7 was directly molded and evaluated. Comparative Example 6 Example 8 was repeated except that the substantially linear polyacetal resin B′-1 obtained in Reference Example was used instead of the branched polyacetal resin B-1.
Samples were prepared and evaluated in the same manner as in.

[0017]

[Table 1]

[0018]

[Table 2]

[0019]

As is apparent from the above description and Examples,
The composition of the present invention suppresses the peeling of the surface layer as seen in the conventional blending of polypropylene resin and polyacetal resin, and has improved mechanical strength, heat resistance and friction characteristics while maintaining the versatility of polypropylene resin. Therefore, its application is expected to expand.

Claims (3)

[Claims] (1) 100 parts by weight of (A) polypropylene resin, (B) 99.88-85.00% by weight of trioxane, and 0.1-10
% By weight of cyclic ether and / or cyclic formal;
A polypropylene resin composition comprising 3 to 100 parts by weight of a branched polyacetal resin obtained by polymerizing 02 to 5% by weight of a diglycidyl compound. 2. The polypropylene resin composition according to claim 1, wherein the diglycidyl compound of the branched polyacetal resin (B) is an alkylene oxide diglycidyl ether. 3. The composition according to claim 1, further comprising 0.01 to 15 parts by weight of a polyisocyanate or a modified product thereof and 0.1 to 30 parts by weight of a modified polypropylene having an active hydrogen group capable of reacting with an isocyanate group. A polypropylene resin composition comprising: